Method of destroying undesirable plants



Patented Apr. 27, 1954 METHOD OF DESTBOYIN G UNDES-IRABLE PLAN TS Arthur H. Schlesinger, Dayton, Ohio, assignor to Monsanto Chemical Company, -St. Louis, Mo., a corporation of Delaware ENT OFF] CE ,No Drawing. Application August 23, 1952, 'Serial No. 306,064

(Cl. ll-+2.3)

6 Claims.

1 The present invention provides new and highly valuableherbicidal compositions and methods of destroying or preventing plant growth for which said compositions are employed.

plants.

. 2 I r with said media. Generally, spraying of only the soil surface is suflicient to prevent plant growth in areas which are to be .keptclear of However, theemulsions may be incor- I have'found that'improved andveryeli'icient 5 porated; into customarily employed temporary herbicidal compositions are obtained when there surfacing materials, e. g., soils, cinders, etc. are prepared oil-in-water emulsions of a ketone The oil-in-water emulsions of the present selected from the class consisting of mand naphthyl alkyl-ketones-are particularly valuable ,B-naphthyl alkyl ketones in which the alkyl in that when applied to the leaves of broadradical has from 1 to 4 carbon atoms. Examples leafed plantathey cau-seleaf-drop. Application of ketones useful for the present purpose are of some of the present herbicidal compositions to a-naphthyl methyl -ketone, fl-naphthyl methyl suchplants as cotton, beans'and peasdefoliates ketone, a-naphthyl propyl lzetone, fi-naphthyl the plants and thus permitsmore efficient isobutyl ketone and oc-naphthyl n-butyl ketone. mechanical harvesting or hand-picking of the The present ketones are readily obtainable, for bolls or pods. i example by reaction of naphthalene with an acyl The present invention is further illustrated, halide or with an acid-anhydride in the presence but not limited, by the following examples. of a Friedel-Crafts type catalyst, by oxidation of a v oaor s-alkylnaphthalene, etc. Example I Herbicidal compositions containing the present Spray testing f the present herbicidal naphthyl alkyl ketones may be readily obtained pe'sitions was d ct d as-fouowsz 1 by first preparing a solution of the ketone in an ypuegpemive cyclohexanone soluti us of mwhorganic solvent and then adding the resulting thyl mEthy} ketoneand fimaphthm methyl solution to water containing an emulsifying agent tone togethgr th an emulsifying agent were reto form an emulsion- Because of the Very high 5 spectively added to water, the quantity of solution herbicidal efficiency of the naphthyl alkyl employed being calculatedgto give emulsions con- Vines, they are present in the herbicidal taining 0.3"per cent and Lflpercent oithe naphpositions in only very small concentrations, for thyl methm ketone, respectively, based on t example, in concentrations of from 0.1 per cent total Weight of each emulsion The t t of in 2.6 percent by weight of the total weight 0f emulsifying agent used was 0.2 per cent by weight, the emulsiol'l- Emulsifymg agents which may be based on the total weight of each emulsion. Said employed are those customarily used in-the art emulsifying agent comprised a i t of for the preparation of oil-in-water emulsions. polyalkyleneglycm derivative and an a'lkylbem The word oil is here used to designate any zenesulfonatg liquid which is insoluble in water. wamples of 1 cornand beanplams, pegpece l fy agents which y be used include tively, were sprayed with the emulsions, two akylb nze lf n a ned -p0lyalky1 plants of each variety being employed. The ene glycols; long-chained succinates, etc. The spraying was continued until droplets formed. emulsions y b used 130 destroy already eXiSton and/orfellfrom-the foliageand stems of the ns plant growt by direfit appli-flation 6030118 40 sprayed plants, upto 15 rnL'of the emulsion being undesirable p a a y p yin or the applied to each plant. The sprayed plants as emulsions y be p fly prevent plant well as two untreated blank specimens of each growth'by application to media which normally plantwere'then'allowed-to remainiunder standard support plant growth. When employed to preconditionsof sunlight'and wateringfor a period vent plant growth, for example, in parking areas, of one-week. Atthe end of that'timev the sprayed highway abutments, railway yards, etc, the plantsjiwerecompared' with-the untreated plants emulsions may be applied by spraying only the in order to determine the extent of injury, if any. surface of said media or they may be admixed The following observations were made:

At per- Extent of Injury cent Compound tested Cong On Bean On Corn B-napthylmethyl ketona. 1.0 Severe iniuryyLeaves Plant dead; Leaves dropped. dried. Do 0.3 None Slight. a-napthyl methyl ketone.. 1.0 Severe injury P5111121 dead; Leaves Do 0.3 None Slight:

Example II Another method of testing for herbicidal efliciency of a chemical involves noting the effects on seed germination and plant growth which may be evidenced by spraying soil surfaces. This test, commonly known as a pre-emergence test was conducted as follows:

Boxes having a 5" x 5" exposed area were partially filled with a layer of soil and seeds were placed thereon and then covered with a A,." to layer of soil which had been screened to A1. sieve. Test boxes containing 20 seeds each of cucumber, rye grass, radish and beet seeds, respectively, were prepared. The surface soil of the seeded boxes was then sprayed, respectively, with the 1.0 per cent and the 0.3 per cent emulsions of Example I. The quantity of each emulsion which was applied was calculated to correspond to either 20 pounds of the ketone per acre or to 50 pounds per acre. In the present instance, 10.8 cc. of the 0.3 per cent emulsion per square inches of surface soil was calculated to correspond to 20 pounds of the chemical per acre and 9.1 cc. of the 1.0 per cent emulsion to pounds of the chemical per acre. ihe sprayed boxes as Well as similar seeded but unsprayed boxes were then maintained at standard conditions of temperature and watering for a period of two weeks. At the end of that time the number of healthy seedlings in each box was counted. Thus the number of non-emerging and damaged seedlings was obtained by difference. This difference is designated as X. Percent phytotoxicity was determined by the ratio of T to the number of healthy seedlings in the controls.

There was evidenced a 71-100 per cent phytotoxicity to beets, radishes and rye grass for the anaphthyl methyl ketone at the 50 pound per acre rate of application and a phytotoxicity of up to 46 per cent of cucumbers at the same rate of application. At the 20 pound rate there was evidenced a phytotoxicity of the unaphthyl methyl ketone of from 71-100 per cent against beet, of from 46-71 per cent for radish and rye, and of up to 46 per cent against cucumber. The 5-naphthyl methyl ketone did not show so marked an activity. With this ketone there was demonstrated at the 50 pound per acre rate of application of ketone of a phytotoxicity of 71-400 per cent against beet, 46- 71 per cent against rye grass, and up to 46 per cent against radish and cucumber. At the 20 pound per acre rate of application, the ,B-naphthyl methyl ketone showed a phytotoxicity of up to 46 per cent against beet but no phytotoxicity against cucumber, radish, or rye grass.

Ercample III While the present naphthyl alkyl ketones are most advantageously employed as herbicides by incorporating them into aqueous emulsions as herein described they may also be employed in other plant destroying methods. Thus they may be incorporated into solid carriers such as clay, talc, pumice, and bentonite to give herbicidal compositions which may be applied to living plants or to surfaces which are to be freed from plant growth. The ketones may also be mixed with liquid or solid agricultural pesticides, e. g., insecticides and fungicides. While solutions of the compounds in organic solvents may be employed for preventing and destroying plant growth, we have found that the emulsions possess and improved tendency to adhere to the reated surfaces and that less of the active ingredient, i. e., the naphthyl alkyl ketones, are required to give comparable herbicida1 efficiency.

What I claim is:

1. The method of destroying undesirable plants which comprises applying to said plant a toxic quantity of a herbicidal composition comprising a ketone selected from the class consisting of lit-naphthyl alkyl ketones and ,B-naphthyl alkyl ketones in which the alkyl radical has from 1 to 4 carbon atoms.

2. The method of preventing plant growth which comprises applying to media normally supporting said growth, a herbicidal composition comprising a ketone selected from the class consisting of oc-l'lELDhthYl alkyl ketones and cnaphthyl alkyl ketones in which the alkyl radical has from 1 to 4 carbon atoms.

3. The method of defoliating plants which comprises applying to the foliage of the said plants a herbicidal composition comprising a ketone selected from the class consisting of o:- naphthyi alkyl ketones and [3-naphthyl alkyl ketones in which the alkyl radical has from 1 to 4 carbon atoms.

4. The method of destroying undesirable plants which comprises applying to said plants a toxic quantity of a herbicidal composition comprising an oil-in-water emulsion of a ketone selected from the class consisting of lac-naphthyl alkyl ketones and ,B-naphthyl alkyl ketones in which the alkyl radical has from 1 to 4 carbon atoms.

5. The method of destroying undesirable plants which comprises applying to said plants a toxic quantity of a herbicida1 composition comprising an oil-in-water emulsion of a-naphthyl methyl ketone.

6. The method of destroying undesirable plants which comprises applying to said plants a toxic quantity of a herbicidal composition com-- prising an oil-in-water emulsion of ,c-naphthyl methyl ketone.

References Cited in the file of this patent UNITED STATES PAENTS Number 

1. THE METHOD OF DESTROYING UNDESIRABLE PLANTS WHICH COMPRISES APPLYING TO SAID PLANT A TOXIC QUANTITY OF A HERBICIDAL COMPOSITION COMPRISING A KETONE SELECTED FROM THE CLASS CONSISTING OF A-NAPHTHYL ALKYL KETONES AND B-NAPHTHYL ALKYL KETONES IN WHICH THE ALKYL RADICAL HAS FROM 1 TO 4 CARBON ATOMS. 